I am trying to write a report that takes a value from the previous row and subtracts it from the value in the current row. I used the previous function to get the value from the previous row. Previous(Fields!num.Value). I soon found that becuse of my grouping the first row in the next group was getting the value of the last row in the previous group. The documentation shows that previous has 2 contructors. you can pass just the value as object or the object and scope as string. So I put in =Previous(Fields!Num.Value,"tabel1_Name") It doesn't show any errors when I save it, but when I preview the report it does not compile saying he Value expression for the textbox textbox9 has an incorrect number of parameters for the function Previous. I'm guessing the documention is wrong. Does anyone now how to correctly pass the scope to the previous function? Is there an additional parameter I need to pass?